Friends of Mr Mackay said he believes he has been “victimised” after Nicola Sturgeon appeared to blame him for giving the green light to the contract.
Two ferries under construction at Ferguson Marine shipyard in Port Glasgow are now set to be at least four years late and around £150 million over budget.
Mr Mackay has not set foot in Holyrood since he resigned as finance secretary in February 2020 over messages sent to a 16-year-old schoolboy.
Speaking publicly for the first time since his downfall, he said: "I am willing to co-operate with a parliamentary committee and do my best to answer any questions they may have.
"To do so as comprehensively as possible I will seek access to the necessary papers and information that I am entitled to as a former government minister."
A friend of Mr Mackay told The Sunday Times: "Derek believes he has been victimised in this whole affair and he is happy to appear at the committee where he will set the record straight and deal with the facts.
"He says, in fact, he was fourth in the pecking order around these ferry orders, as junior transport minister – the most junior of those dealing with them. He was behind the main players – Nicola Sturgeon, John Swinney and Keith Brown.
"Anyone who knows anything about the way these processes work knows something of this size could never have happened without prior approval at the highest levels."
A report by Audit Scotland recently raised concerns over a lack of documentation to explain why the ferries contract was signed off without a refund guarantee that would have protected public money, and despite concerns raised by government ferries agency CMAL.
Holyrood's public audit committee is now expected to launch a probe into the debacle.
Scottish Conservative MSP Graham Simpson welcomed Mr Mackay’s statement.
He told the BBC’s Sunday Show: "I think that would be a good thing if he comes before the public audit committee, because what we don't know so far – because the Government has not told us – is why the decision was taken to ignore CMAL's advice.
"They were saying 'don't give that contract to Ferguson's’.
"We do not know yet why that decision was taken or indeed who took it.
"The SNP are trying to blame Derek Mackay, so I'm not surprised that he wants to come forward and speak to a committee."
Scottish Labour leader Anas Sarwar said: "I think it's right that he comes to give evidence.
"I think it's frankly laughable for the Government to suggest that we don't have a control freak government, and we don't have a micromanaging First Minister.
"The idea that such a big decision was taken by a junior minister without the approval of the First Minister is unbelievable."